“The amount of of tax equity financing available may decline given then the lower tax rate, which could potentially be negative for First Solar and SunPower,” Ben Kallo

So maybe this could be the cause for the drop. I remember seeing research notes from Credit Suisse in the spring that were analyzing the effect on tax equity value given that companies will have less tax to apply credits to.

“The amount of of tax equity financing available may decline given then the lower tax rate, which could potentially be negative for First Solar and SunPower,” Ben Kallo

So maybe this could be the cause for the drop. I remember seeing research notes from Credit Suisse in the spring that were analyzing the effect on tax equity value given that companies will have less tax to apply credits to.

except the credit is 30% and applies as a lump sum. Interpretation is the key here.